1. Field of the Invention
The present invention relates to a position indicator formed by winding a coil around a ferrite core, and a coordinate input device equipped with the position indicator. More particularly, the present invention relates to a position indicator in which an external impact force transmitted to a ferrite core and a rod passing through the ferrite core can be absorbed or alleviated, and a coordinate input device equipped with such position indicator.
2. Description of the Related Art
In recent years, a coordinate input device has been used as an input device for a personal computer, for example. Such a coordinate input device is configured by a pen-like position indicator and a position detecting device having an input surface where an input operation is performed using the position indicator, such as a pointing operation, a handwritten character input operation, and/or a hand-drawn illustration input operation.
Further, as a drive method for performing the position detecting, there is a drive method called “electromagnetic induction method” in which the position indicator is provided with a resonant circuit, which resonates with an electromagnetic wave of a specified frequency transmitted from the position detecting device, and the position of the position indicator relative to the position detecting device is indicated by transmitting a resonant signal from the position indicator to the position detecting device.
In the aforesaid electromagnetic induction method, the position indicator includes a position detecting coil and a capacitor forming the resonant circuit, and a rod passing through the position detecting coil. Generally, the position detecting coil is wound around the periphery of a cylindrical ferrite core, and the rod passes through a hole of the ferrite core (see, for example, Japanese Unexamined Patent Application Publication No. 2001-319831, corresponding to U.S. Pat. No. 6,853,369, which is incorporated by reference herein). The purpose of winding the position detecting coil around the periphery of the ferrite core is to increase the magnetic field intensity so as to improve the accuracy of position detection.